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# Kinetics: Rate Law

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i am clarifying this is not an assignemt is just practice questions. It was part of an old test that the teacher gave to us to practice .

This are practice questions
1. Calculate deltaH for the reaction P4O10 + 6 PCl3 ----? 10 Cl3PO

From
P4 + 6 Cl2 -----> 4 PCl3 deltaH = -1225.6 kJ
P4 + 5 O2 -----> P4O10 deltaH = -2967.3 kJ
PCl3 + Cl2 -----> PCl5 deltaH = -84.2 kJ
PCl3 + ½ O2 ---> Cl3PO deltaH = -285.7 kJ

2. Experiment

................[HgCl2]M............ [C2O4-2]M........ Rate(M/sec)
1..................0.105....................0.15...............1.8 x 10-5
2 .................0.105....................0.30...............7.2 x 10-5
3...................0.052...................0.30...............3.5 x 10-5
4..................0.052....................0.15...............8.9 x 10-6
5 .................0.200....................0.45.....................X
6..................0.35..........................y.................5.0 x 10-5

a) Determine the rate law
b) Calculate k
c) Determine the values for X and Y
3. Butadiene, C4H6, dimerizes to C8H12 with a 1st order rate constant of 0.014 L/mol sec. Starting with 0.025 M
a) What will be the concentration after 3.00 minutes?
b) How long will it take the concentration to drop to 0.0065 M?

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https://brainmass.com/chemistry/chemical-kinetics/kinetics-rate-law-527558

#### Solution Preview

1.
6PCl5 -> 6PCl3+6Cl2 (-6*(III))
10PCl3+5O2 -> 10Cl3PO (10*(IV))
P4O10 -> P4+5O2 (-(II)).
(I)-6*(III)+10*(IV)-(II): we could obtain our reaction.
Delta H = -1225.6-6*(-84.2)+10*(-285.7)-(-2967.3)= -610.1 kJ

2.
a)
When [C2O4-2] ...

#### Solution Summary

The expert calculates deltaH for a reaction using kinetic rate laws.

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See Also This Related BrainMass Solution

## Reaction Kinetics, Rate Laws and Equilibrium

1. The isomerization of cyclopropane to form propene

CH3 - CH CH2CH2

is a first-order reaction. At 760 K, 15 percent of a sample of cyclopropane changes to propene in 6.8 minutes. What is the half-life of cyclopropane at 760 K?

2. Consider the two gaseous equilibria (K1 and K2):

SO2(g) + ½O2(g) SO3(g) K1

2SO3(g) 2SO2(g) + O2(g) K2

The values of the equilibrium constants K1 and K2 are related by ________.

3. The following reactions occur at 500 K. Arrange them in order of increasing tendency to proceed to completion (i.e., least completion greatest completion).
1. 2NOCl 2NO + Cl2 KP = 1.7 x 10-2
2. N2O4 2NO2 KP = 1.5 x 103
3. 2SO3 2SO2 + O2 KP = 1.3 x 10-5
4. 2NO2 2NO + O2 KP = 5.9 x 10-5

4. On analysis, an equilibrium mixture for the reaction

2H2S(g) 2H2(g) + S2(g)

was found to contain 1.0 mol H2S, 4.0 mol H2, and 0.80 mol S2 in a 4.0 L vessel. Calculate the equilibrium constant for this reaction.

5. At 35oC, the equilibrium constant for the following reaction is Kc = 1.6 x 10-5.

2NOCl(g) 2NO(g) + Cl2(g)

An equilibrium mixture was found to have the following concentrations of Cl2 and NOCl:

[Cl2] = 1.2 x 10-2 M; [NOCl] = 2.8 x 10-1 M. Calculate the concentration of NO(g) at equilibrium.

6. For the following reactions the equilibrium constants are defined.

A + 2B C K1
C D + E K2

Then for the reaction

A + 2B D + E Kc

the equilibrium constant must be equal to ________.

7. At 700 K, the reaction

2SO2(g) + O2(g) 2SO3(g)

has an equilibrium constant Kc = 4.3 x 106, and the following concentrations are present:

[SO2] = 0.10 M
[SO3] = 10 M
[O2] = 0.10 M

Is the mixture at equilibrium? If not at equilibrium, in which direction-left to right or right to left- will the reaction occur to reach equilibrium?

8. For the following reaction at equilibrium, which choice gives a change that will shift the position of equilibrium to favor formation of more products?

2NOBr(g) 2NO(g) + Br2(g) Horxn = 30 kJ

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